The present invention relates to automatic dispensers used in liquid holding tanks in which the liquid level changes, and in particular to such dispensers which dispense cleaner from a container into a toilet overflow tube.
A variety of dispensers exist for automatically dispensing chemicals into a water tank such as a toilet tank. Some toilet bowl cleaner dispensers use a float valve which opens and closes with changes in the toilet tank level during a flush cycle. For example, U.S. Pat. No. 5,903,930 describes a toilet cleansing agent dispenser having a cylindrical housing, a receiving body, and a float piece. The cylindrical housing is provided with a frame for mounting the dispenser in a toilet water tank. The float piece is capable of up-and-down displacement in accordance with the water level in the toilet water tank, so as to regulate the flow of the toilet cleansing agent from the receiving body into the toilet water tank.
As the water level in the toilet water tank rises to a certain level after the flush, the float piece seals off the flow hole of the receiving body so as to terminate the flow of the cleansing agent into the toilet water tank. This type of dispenser can be inefficient. First, many such automatic liquid dispensers have a tendency for the product that is being dispensed to leak out of the dispenser in a somewhat uncontrolled manner which can result in overdosing of the product. Second, the objective is to keep the toilet bowl clean, not the water holding tank. Since all the cleaner is dispensed into the tank, rather than the bowl, most of the cleaner is flushed down the drain without cleaning the toilet bowl at all.
It has been recognized that cleaner can be dispensed into the toilet overflow tube rather than into the toilet tank. For example, U.S. Pat. No. 3,254,797 describes a liquid chemical dispenser that is attached to the overflow pipe with a float positioned beneath the water in the toilet tank. Upon flushing, the water moves downward allowing the float to move downward to flex a diaphragm downwardly. This opens an inlet valve which allows liquid to fill the diaphragm cavity above the diaphragm. As the toilet tank refills with water, the float moves upward to flex the diaphragm upwardly to discharge liquid from the cavity above the diaphragm and into the overflow pipe.
U.S. Pat. No. 6,321,392 describes another example device that dispenses cleaner into the toilet overflow tube. The device uses a solid puck of a chlorine donor. A body member receives the solid puck of cleaning agent. An inlet is in communication with the body member and is connectable to a ball cock through a refill tube, and an outlet is in communication with the body member and is connectable to the toilet overflow pipe through a connecting hose. The device delivers water and dissolved cleaner to the toilet overflow tube as the tank fills after a flush. However, the use of a solid puck results in inconsistent release of actives to the toilet bowl, particularly when the puck is near the end of its life.
U.S. Pat. No. 5,353,957 describes yet another example device that dispenses cleaner into the toilet overflow tube. The device includes a container for holding a liquid cleaner, a dispensing nozzle, and a sensing tube. The dispensing nozzle is positioned on the container below the liquid level within the container. The sensing tube is immersible in the water in the toilet tank, whereby the cyclic fall and rise of the tank water results in the discharge of the liquid from the container through the dispensing nozzle. The container can be clipped to the upper open end of the toilet overflow tube such that the liquid falls from the dispensing nozzle into the toilet overflow tube.
U.S. Pat. No. 5,152,015 describes still another example device that dispenses cleaner into the toilet overflow tube. The dispensing device includes an accumulator chamber having a conduit communicating with the toilet tank water. The accumulator chamber also has a product inductor conduit communicating with a product chamber. The device also includes a first product discharge conduit communicating with the accumulator chamber and a second product discharge conduit communicating with the discharge conduit and extending into the toilet tank overflow pipe. When the toilet tank water level falls during flushing, the water level in the conduit falls, causing a reduced pressure in the accumulator chamber and a rising of the product in the inductor conduit. When the toilet tank fills, the water rises in the toilet tank, compressing the air in the conduit forcing the product to be discharged from the accumulator through the first and the second product discharge conduit and into the toilet tank overflow pipe.
Notwithstanding this variety of devices which dispense cleaner into a toilet overflow tube, a need still exists for improved dispensers for delivering an accurately controlled volume of liquid cleaner into a toilet overflow tube at a time when it will remain in the toilet bowl until the next flush.